Editing Mechanical pencil (section)

===Diameter===
Mechanical pencil mechanisms use only a single lead diameter. Some pencils, such as the [[Pentel]] Function 357, place several mechanisms within the same housing, so as to offer a range of thicknesses (in this case three: 0.3, 0.5 and 0.7&nbsp;mm). 1.00&nbsp;mm leads also exist, but they are very rare. (See table below.)

Different sizes of lead diameters are available to accommodate various preferences and pencil builds, as shown in the table below. The more common lead sizes are 0.5&nbsp;mm and 0.7&nbsp;mm, whose line widths provide a favourable balance between precision and strength. Less common lead sizes can range from 0.2&nbsp;mm up to 5.6&nbsp;mm. [[Pentel]] has also previously demonstrated a prototype 0.1&nbsp;mm pencil.<ref>{{Cite web|url=http://www.nichima.co.jp/news/entry/1747.html|title=ニュース - 文マガ|website=www.nichima.co.jp|access-date=2017-05-07}}</ref>
Pencils with sub-millimeter leads can usually hold multiple leads at the same time, reducing the frequency of refills. One exception was the Pentel 350 E, possibly Pentel's first mechanical pencil,<ref name=Pentel350>{{cite web |url=http://www.leadholder.com/lh-thin-pentel-350.html |title=Pentel 350 Series Mechanical Pencil {{!}} Leadholder |publisher=Leadholder.com |accessdate=November 14, 2010}}</ref> which could only hold a single stick of 0.5&nbsp;mm lead. Refill leads can be bought in small tubes and inserted into the barrel as needed.

{| class="wikitable"
|-
! Diameter<br> (mm) !! Uses
|-
| 0.20 || technical work (by Pentel for his Orenz pencils)
|-
| 0.30 || technical work (also known as 0.35&nbsp;mm in certain German manufacturers)
|-
| 0.40 || technical work (only available in Japan)
|-
| 0.50 || general writing, general technical work, beginner's technical work
|-
| 0.70 || general writing
|-
| 0.80 || general writing
|-
| 0.90 || students/general writing (also known as 1.0&nbsp;mm in certain German manufacturers)
|-
| 1.00 || rare, used in pre-1950 Parker pencils
|-
| 1.18 || older, used in pencils like the [[Yard-O-Led]]
|-
| 1.30 || [[Staedtler]] and Pentel (colour leads only for Pentel). Also Kokuyo and Paper Mate
|-
| 1.40 || [[Faber-Castell]] e-Motion and the new [[Lamy]] ABC as well as some [[Schwan-Stabilo|Stabilo]] children's pencils
|-
| 2.00 || drafting leadholders
|-
| 3.15 || non-drafting leadholders ([[Lamy]], [[Faber-Castell]], [[Schwan-Stabilo|Stabilo]] and Worther)
|-
| 3.20 || non-drafting leadholders ([[Kaweco]] and [[Koh-i-Noor Hardtmuth|Koh-I-Noor]])
|-
| 3.80 || non-drafting leadholders ([[Koh-i-Noor Hardtmuth|Koh-I-Noor]] and Pilot for his Croquis pencils)
|-
| 5.20 || non-drafting leadholders (by Milan, a Spanish brand)
|-
| 5.60 || non-drafting leadholders ([[Kaweco]], [[Koh-i-Noor Hardtmuth|Koh-I-Noor]], Worther)
|}